What primary alloying elements are typically found in structural steels__________________?
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Answer: A. nickel, chromium and manganese
Explanation
Structural steels are carbon-manganese steels where alloying elements are deliberately added to improve mechanical performance beyond plain carbon steel limits. Nickel and chromium are added to enhance toughness, hardenability, and atmospheric corrosion resistance in demanding structural applications. Manganese acts as a powerful deoxidizer while significantly improving tensile strength and hardenability in the steel matrix. Common structural steels like ASTM A36 contain controlled amounts of carbon, manganese, silicon, sulfur, and phosphorus. Alloying elements form solid solutions or precipitates that hinder dislocation movement, thereby increasing the yield strength of the material. Micro-alloying additions are kept within strict percentages to maintain good weldability and ductility while boosting strength.
Option B lists elements like tungsten and molybdenum that are typically reserved for high-speed tool steels rather than standard structural grades. Option C includes lead and tin, which cause embrittlement and hot shortness rather than serving as beneficial structural alloying additions. Option D includes excessive sulphur, which forms inclusions and degrades steel quality, making it an incorrect primary alloying choice.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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